1. Field of the Invention
The present invention relates to an image processing method, an image output apparatus, and a display apparatus for executing color management processing using display characteristic information of an image display apparatus.
2. Description of the Related Art
There is a technique called color management for performing matching of colors by converting colors among different devices in a digital camera, a monitor, a printer, and the like into united colors and processing the colors. In the color management, colors are converted into device dependent colors (RGB or CMYK) or device independent colors (CIE-XYZ or CIE-L*a*b*) and matched. The device dependent colors represent colors that are different, depending on the devices on which they are displayed. Therefore, for example, even if RGB values are the same, colors of an image photographed by a certain digital camera and the colors displayed when the same RGB values are input to a monitor are different. The device independent colors are indexes of united colors not depending on the devices on which they are displayed. For example, colors having the same CIE-XYZ values look the same when viewed on the monitor and in an image photographed by the digital camera. In color management, according to correspondence relation information of device dependent colors of an input device and device independent colors, the device dependent colors of the input device are converted into the device independent colors. According to correspondence relation information of device dependent colors of an output device and device independent colors, the device independent colors are converted into the device dependent colors of the output device. Consequently, the output device can output colors the same as the colors of the input device. The common device independent colors at this point are referred to as profile connection space (PCS). Conventionally, as a technique for executing color management processing using correspondence relation information of device dependent colors and device independent colors, a technique for converting colors on the basis of one kind of correspondence relation information determined for each of devices is generally used.
Japanese Patent Application Laid-Open No. 2005-192019 discloses that a matrix coefficient of applied color conversion is changed on the basis of a brightness component value of an input image. However, in the technique of Japanese Patent Application Laid-Open No. 2005-192019, correspondence relation information of devices is one kind of information. The same conversion is performed concerning the same signal irrespective of a state of an image display apparatus.
There is a technique for, even when display characteristics of an image display apparatus such as setting of a color gamut and γ of the image display apparatus are different, expressing colors in a form matching characteristics of the image display apparatus at that point. For example, Japanese Patent Application Laid-Open No. 2007-312057 discloses that a change in parameters inside an image display apparatus is detected and profiles are switched.
On the other hand, as a technique of obtaining high quality images for a monitor, dimming control for adjusting a backlight light amount is examined. In a monitor that makes use of a liquid crystal panel, usually, light of a backlight is irradiated from the back of the liquid crystal panel and transmitted through the liquid crystal panel to express colors. There is a limit in reducing the transmittance of liquid crystal. Therefore, in some cases, even if the transmittance of the liquid crystal is minimized, the light of the backlight is transmitted and sufficient contrast cannot be obtained. On the other hand, there is known a technique for improving contrast by performing dimming control for adjusting a backlight light amount according to an image signal.
As the dimming control, there are global dimming for uniformly changing a light amount of the entire backlight and local dimming for dividing the backlight into several control regions (hereinafter LD regions) and changing a light amount independently for each of the divided LD regions.